I think we're so used to ounces per square foot we'd have to do a conversion before we'd have any idea what our wing loading was! I know I have to mentally convert kilometers to miles before I can get a feel for how far it "really" is. I also tend to convert ounces to pounds if the ounces get much over 60 or I'm lost. Tell me a plane weighs 128 ounces and I've got to change it to eight lbs. Same with millimeters. I have to do a quick rough headspace conversion before I can sense a 12 mm something is a bit less than half an inch. I wish I'd grown up metric, as it IS much simpler!